Effect of Annealing on the Mechanical and Thermomechanical Characteristics of the Ti 50 Pd 40 Ni 10 High-Temperature Sha
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NGTH AND PLASTICITY
Effect of Annealing on the Mechanical and Thermomechanical Characteristics of the Ti50Pd40Ni10 High-Temperature Shape Memory Alloy Studied on the Rod-Like Blank N. N. Popova, *, D. V. Presnyakova, V. F. Lar’kina, I. S. Ryzhova, and A. A. Kostylevaa aRussian
Federal Nuclear Center All-Russian Research Institute of Experimental Physics, Sarov, Nizhny Novgorod oblast, 607188 Russia *e-mail: [email protected]
Received September 19, 2019; revised January 21, 2020; accepted March 24, 2020
Abstract—The properties of the Ti50Pd40Ni10 (at %) alloy showing the high-temperature shape memory effect are studied in detail using samples made of a 5.86 mm bar under various conditions of annealing and induced deformation. The data on the phase transformation temperatures and the mechanical and thermomechanical characteristics of the alloy are obtained. The range of phase transformations occurs in the range from Mf = 360°C to Af = 439°C. These are acceptable values for creating the required safety device. The maximum values of the shape memory effect and the degree of shape recovery are 2.4 and 43%, respectively. This is not sufficient to create a functional security device. Thus, the selection of annealing modes and conditions for inducing deformation are not a successful way to substantially increase the thermomechanical characteristics of the alloy. Higher values of thermomechanical characteristics have previously been obtained using samples cut from a strip with a thickness of 2.04 mm. Therefore, operating elements of safety devices designed for nuclear power facilities will be further manufactured from the strip. Keywords: effect of annealing, conditions for inducing strain, Ti50Pd40Ni10 alloy, high-temperature shapememory effect, bar, differential thermal analysis, mechanical characteristics, thermomechanical characteristics DOI: 10.1134/S0031918X20080074
INTRODUCTION We chose the Ti50Pd40Ni10 alloy (at %) with hightemperature shape memory effect to manufacture temperature sensitive elements of the safety device designed for fast breeder nuclear reactors. Using the samples made from a strip with a thickness of 2.04 mm in [1] and from a bar with a diameter of 5.86 mm in [2], we studied the properties of this alloy in the initial state. However, it was found that the maximum values of the shape memory effect (SME) and the degree of shape recovery for the bar are 1.5 and 21%, respectively. This is not enough to create a functional security device. It was planned to increase these characteristics by selecting the optimal conditions for the heat treatment and deformation for the objects under study. The results of these studies are reported in this paper. MATERIALS AND TECHNIQUES The studies were carried out on an alloy with composition 33.1Ti–58.8Pd–8.1Ni (numbers indicate wt % in the batch mixture) or Ti50Pd40Ni10 (at %) supplied in the form of a bar marked by the manufacturer with L. After manufacturing, the bar was annealed in a vacuum
at a temperature of 850°C for 1 h in a resistance vacuum furnace SShV
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